My father-inlaws '05 dakota has started to over heat. He found the radiator had a small leak, so he added some stop leak to it. Things got worse. Overheated on way to my house, after dinner we looked at it and found it low on coolant and over flow tank empty with lid blown off. Refilled will 50/50 mix and ran engine in drive way. Coolant in radiator never got hot, air temp. But gauge read normal at half way mark. I suspected bad T-stat. We drove it to his mechanics shop about 10 miles away, about 5 miles in started to over heat and almost peg gauge. We turned on heat all the way and fan on high. Drove rest of way, slowly. Upon parking, we ran it and temp came down to half way. He had the radiator replaced and new thermostat installed,cooling system flushed, but it still overheats. Changed oil and looked good no signs of coolant. Very strange???? Truck has heat, upper hose hot, but lower hose cold. No further lose of coolant. Any ideas. Truck has 3.7 v6 with 150,000 miles
Over heating Dakota
- Thread starter Trackrat73
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Impeller spinning on the shaft of the water pump, or it just might be rotted away. A low flow situation. Are the heater hoses getting hot?
Head gaskets aren't uncommon for the 3.7, that's for sure
The 4.7/3.7 for some range of years had situation where the impeller on the WP shaft would tend to let go and slip at higher RPMs. Looks like everything is working at idle, but the cooling system can't keep up under load and at speed where the slippage gets worse. Since you've covered all the basics, that would probably be the next place I'd look.
Nick1994
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Here's 2 of my personal situations with overheating. They're a bit lengthy.
2002 Chevy Trailblazer. Engine hardly warmed up (OE thermostat stuck open), put in new Stant thermostat. 2 weeks later it started running a bit warm, 3/4 on the temp gauge. Replaced thermostat with another Stant. No change in temp. Replaced radiator, thought it might be clogged. No change in temp. Changed thermostat to OEM from dealership, it helped quite a bit. The Stant thermostat's opening was over 10% smaller than OEM, I measured it myself with a micrometer. You could see it with the bare eye that it was smaller. It still ran a little warm though. I changed the original radiator cap (didn't replace when radiator was replaced) and that has 100% fixed the issue. The temperature gauge is now always at 1/3-1/2 even at 80 mph in the mountains or in 110 degree heat. 108k miles now
2003 Buick Rendezvous. Original thermostat stuck closed, engine overheated and blew the head gasket. It's been almost a year and my mom still daily drives it, sometimes it gets to running hot though in certain driving conditions. The way the head gasket is blown, is that Exhaust gases are getting into the coolant and filling the radiator, the upper house of the radiator is constantly full of air, it will never bleed out because it's being constantly pumped with exhaust gases. It also loses about 2 gallons of coolant per month consistently, there is no external leaks and it isn't ending up in the oil. The coolant is also getting into the exhaust, and burning off into some kind of steam.
It still runs great though, surprisingly. 148k miles now
2002 Chevy Trailblazer. Engine hardly warmed up (OE thermostat stuck open), put in new Stant thermostat. 2 weeks later it started running a bit warm, 3/4 on the temp gauge. Replaced thermostat with another Stant. No change in temp. Replaced radiator, thought it might be clogged. No change in temp. Changed thermostat to OEM from dealership, it helped quite a bit. The Stant thermostat's opening was over 10% smaller than OEM, I measured it myself with a micrometer. You could see it with the bare eye that it was smaller. It still ran a little warm though. I changed the original radiator cap (didn't replace when radiator was replaced) and that has 100% fixed the issue. The temperature gauge is now always at 1/3-1/2 even at 80 mph in the mountains or in 110 degree heat. 108k miles now
2003 Buick Rendezvous. Original thermostat stuck closed, engine overheated and blew the head gasket. It's been almost a year and my mom still daily drives it, sometimes it gets to running hot though in certain driving conditions. The way the head gasket is blown, is that Exhaust gases are getting into the coolant and filling the radiator, the upper house of the radiator is constantly full of air, it will never bleed out because it's being constantly pumped with exhaust gases. It also loses about 2 gallons of coolant per month consistently, there is no external leaks and it isn't ending up in the oil. The coolant is also getting into the exhaust, and burning off into some kind of steam.
It still runs great though, surprisingly. 148k miles now
ok, I'm gonna look at the pump and pressure test the system. I have to find one of those head gasket test kits. I spoke with him this morning and after his short drive to work he popped the hood and said the upper hose is hot but lower is cold???? I know the T-stat is in the lower hose on these dodges. Could it be faulty T-stat? Cause if its the head gaskets, time to go Truck shopping. BtW could an air pocket cause this?
Originally Posted By: Trackrat73
ok, I'm gonna look at the pump and pressure test the system. I have to find one of those head gasket test kits. I spoke with him this morning and after his short drive to work he popped the hood and said the upper hose is hot but lower is cold???? I know the T-stat is in the lower hose on these dodges. Could it be faulty T-stat? Cause if its the head gaskets, time to go Truck shopping. BtW could an air pocket cause this?
CLASSIC symptom of too little coolant flow. Since you've done the T-stat and also done the radiator, I'm more convinced than ever that the water pump impeller is free on the shaft. Yes, it could be a faulty T-stat, and yes it could be an air pocket, but given the history of water pump failure those are lower on my list.
ok, I'm gonna look at the pump and pressure test the system. I have to find one of those head gasket test kits. I spoke with him this morning and after his short drive to work he popped the hood and said the upper hose is hot but lower is cold???? I know the T-stat is in the lower hose on these dodges. Could it be faulty T-stat? Cause if its the head gaskets, time to go Truck shopping. BtW could an air pocket cause this?
CLASSIC symptom of too little coolant flow. Since you've done the T-stat and also done the radiator, I'm more convinced than ever that the water pump impeller is free on the shaft. Yes, it could be a faulty T-stat, and yes it could be an air pocket, but given the history of water pump failure those are lower on my list.
Originally Posted By: Trackrat73
Overheated on way to my house, after dinner we looked at it and found it low on coolant and over flow tank empty with lid blown off.
Overheated on way to my house, after dinner we looked at it and found it low on coolant and over flow tank empty with lid blown off.
Originally Posted By: Doog
Originally Posted By: Trackrat73
Overheated on way to my house, after dinner we looked at it and found it low on coolant and over flow tank empty with lid blown off.
That could mean blown head gaskets... but MORE LIKELY it means the water pump impeller is not spinning and the coolant violently boiled inside the block, blowing the cap off the reservoir tank and pushing the (cold) liquid coolant in the reservoir out.
Originally Posted By: Trackrat73
Overheated on way to my house, after dinner we looked at it and found it low on coolant and over flow tank empty with lid blown off.
That could mean blown head gaskets... but MORE LIKELY it means the water pump impeller is not spinning and the coolant violently boiled inside the block, blowing the cap off the reservoir tank and pushing the (cold) liquid coolant in the reservoir out.
Ok update. Do to time constraints, I broke down and took the Dakota to friend's shop last nite. He called me today to let me know what he found. Bad bearing in water pump, seized belt idler roller, bad fan clutch, and he said whoever installed the thermostat some how bent it. This is a person I trust and see often, so I know he isn't [censored]'ing me. How this truck ran like this for so long I couldn't say. But know wonder it was over heating. We should get the truck tomorrow, just waiting on fan clutch.
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